Here is the full list of all 57 Star Wars Knights of the Old Republic II: The Sith Lords achievements.
Win a Pazaak game with a full board
Complete the game on the Dark Side
Have your character replace any of the Sith Lords on the main menu screen.
Acquire all Dark Side Powers.
Kill all the Jedi masters
Reduce a companion's Influence to zero.
Side with Vaklu on Onderon
Change your mind about siding with the Settlers at Khoonda
Break Hanharr's spirit
Recruit Hanharr
Listen to HK-47's definition of love.
Acquire all Light Side Powers
Deduce G0-T0's identity
Have 30 points in Demolitions.
Beat the champ on Nar Shadaa
Convince the "champ" to lose the game without playing.
Learn Moving Meditation
Complete the game on the Light Side
Defeat Sion
Claim Darth Nihilus' mask.
Defeat Nihilus
Side with the Queen on Onderon
Flee Korriban after fighting Sion
Get this by starting the "Trapped" Quest on Korriban.
Loot a body on Korriban
Fill the Party Selection screen
Complete the Mandalorian Battle Circle
Learn Force Sight
Convince Vogga the Hutt to sell fuel to Telos.
Side with the Settlers at Khoonda
Contruct your first Lightsaber
Recruit the Disciple
Complete the Handmaiden Battle Circle
Let the Sith destroy the Peragus Asteroids
Kill all Sith troopers before they can board the Ebon Hawk
Install HK-47's unique module
Learn how to kill Jedi from HK-47
Repair the damaged droid on the Ebon Hawk
Recruit Mira
Reach maximum Dark Side points
Complete the Prologue
Have 30 points in Stealth
Reach Player Level 30
Have 30 points in Treat Injury.
Have 30 points in Repair.
Have 30 points in Computer Use.
Teach the Handmaiden the ways of the Force.
Have Persuasion over 30
Gain a Prestige class
Collect 10,000 credits
Get the named Lightsaber crystal
Reach maximum Light Side points
Recruit the Handmaiden
Get your first Dark Side points
Destroy Peragus Astroids
Dance for Vogga
Get your first Light Side points